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platform_system_vold/vold_prepare_subdirs.cpp
Jooyung Han 443a73b100 Use apexservice to get the list of apexes 
In this change, the logic to get the list of apexes is replaced with
the query to apexservice, which is the source of truth. This dedups
the manual scanning of /apex for the apex list, which should be
internal to apexd. (Note how vold_prepare_subdirs filtered out
directories with "@" character).

This also makes vold_prepare_subdirs immune to the upcoming changes:
/apex directory containing only bootstrap APEXes in the bootstrap NS.

Until now, getting the list of apexes by scanning /apex was okay
because of the accidental fact that /apex directory has directories
for all the apexes, not only bootstrap apexes.

Bug: 293949266
Bug: 293546778
Test: CtsPackageSettingHostTestCases
Change-Id: I3fe373ca6f4c2281439bb2449845a1a14357131e
2023-08-01 10:51:49 +00:00

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/*
* Copyright (C) 2017 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*
* Tool to create a directory with the right SELinux context applied, or
* apply the context if it's absent. Also fixes mode, uid, gid.
*/
#include <iostream>
#include <string>
#include <vector>
#include <dirent.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <android-base/logging.h>
#include <android-base/result.h>
#include <android-base/scopeguard.h>
#include <android/apex/ApexInfo.h>
#include <android/apex/IApexService.h>
#include <binder/IServiceManager.h>
#include <cutils/fs.h>
#include <selinux/android.h>
#include "Utils.h"
#include "android/os/IVold.h"
#include <private/android_filesystem_config.h>
static void usage(const char* progname) {
std::cerr << "Usage: " << progname << " [ prepare | destroy ] <volume_uuid> <user_id> <flags>"
<< std::endl;
exit(-1);
}
static bool small_int(const std::string& s) {
return !s.empty() && s.size() < 7 && s.find_first_not_of("0123456789") == std::string::npos;
}
static bool valid_uuid(const std::string& s) {
return s.size() < 40 && s.find_first_not_of("0123456789abcdefABCDEF-_") == std::string::npos;
}
static bool prepare_dir_for_user(struct selabel_handle* sehandle, mode_t mode, uid_t uid, gid_t gid,
const std::string& path, uid_t user_id) {
auto clearfscreatecon = android::base::make_scope_guard([] { setfscreatecon(nullptr); });
auto secontext = std::unique_ptr<char, void (*)(char*)>(nullptr, freecon);
char* tmp_secontext;
if (selabel_lookup(sehandle, &tmp_secontext, path.c_str(), S_IFDIR) == 0) {
secontext.reset(tmp_secontext);
if (user_id != (uid_t)-1) {
if (selinux_android_context_with_level(secontext.get(), &tmp_secontext, user_id,
(uid_t)-1) != 0) {
PLOG(ERROR) << "Unable to create context with level for: " << path;
return false;
}
secontext.reset(tmp_secontext);
}
if (setfscreatecon(secontext.get()) != 0) {
LOG(ERROR) << "Failed to setfscreatecon for directory " << path;
return false;
}
} else if (errno == ENOENT) {
LOG(DEBUG) << "No selabel defined for directory " << path;
} else {
PLOG(ERROR) << "Failed to look up selabel for directory " << path;
return false;
}
LOG(DEBUG) << "Setting up mode " << std::oct << mode << std::dec << " uid " << uid << " gid "
<< gid << " context " << (secontext ? secontext.get() : "null")
<< " on path: " << path;
if (fs_prepare_dir(path.c_str(), mode, uid, gid) != 0) {
return false;
}
if (secontext) {
char* tmp_oldsecontext = nullptr;
if (lgetfilecon(path.c_str(), &tmp_oldsecontext) < 0) {
PLOG(ERROR) << "Unable to read secontext for: " << path;
return false;
}
auto oldsecontext = std::unique_ptr<char, void (*)(char*)>(tmp_oldsecontext, freecon);
if (strcmp(secontext.get(), oldsecontext.get()) != 0) {
LOG(INFO) << "Relabelling from " << ((char*)oldsecontext.get()) << " to "
<< ((char*)secontext.get()) << ": " << path;
if (lsetfilecon(path.c_str(), secontext.get()) != 0) {
PLOG(ERROR) << "Relabelling failed for: " << path;
return false;
}
}
}
return true;
}
static bool prepare_dir(struct selabel_handle* sehandle, mode_t mode, uid_t uid, gid_t gid,
const std::string& path) {
return prepare_dir_for_user(sehandle, mode, uid, gid, path, (uid_t)-1);
}
static bool rmrf_contents(const std::string& path) {
auto dirp = std::unique_ptr<DIR, int (*)(DIR*)>(opendir(path.c_str()), closedir);
if (!dirp) {
if (errno == ENOENT) {
return true;
}
PLOG(ERROR) << "Unable to open directory: " << path;
return false;
}
bool res = true;
for (;;) {
errno = 0;
auto const entry = readdir(dirp.get());
if (!entry) {
if (errno) {
PLOG(ERROR) << "readdir failed on: " << path;
return false;
}
return res;
}
if (entry->d_name[0] == '.') continue;
auto subdir = path + "/" + entry->d_name;
if (0 !=
android::vold::ForkExecvp(std::vector<std::string>{"/system/bin/rm", "-rf", subdir})) {
LOG(ERROR) << "rm -rf failed on " << subdir;
res = false;
}
}
}
static android::base::Result<std::vector<std::string>> get_apex_list() {
auto sm = android::defaultServiceManager();
auto binder = sm->waitForService(android::String16("apexservice"));
if (binder == nullptr) {
return android::base::Error() << "Failed to get apexservice";
}
auto service = android::interface_cast<android::apex::IApexService>(binder);
std::vector<android::apex::ApexInfo> list;
auto status = service->getActivePackages(&list);
if (!status.isOk()) {
return android::base::Error() << status.exceptionMessage().c_str();
}
std::vector<std::string> names;
names.reserve(list.size());
for (const auto& apex_info : list) {
names.push_back(apex_info.moduleName);
}
return names;
}
static bool prepare_apex_subdirs(struct selabel_handle* sehandle, const std::string& path) {
if (!prepare_dir(sehandle, 0711, 0, 0, path + "/apexdata")) return false;
auto apex_list = get_apex_list();
if (!apex_list.ok()) {
LOG(ERROR) << apex_list.error();
return false;
}
for (const auto& name : *apex_list) {
if (!prepare_dir(sehandle, 0771, AID_ROOT, AID_SYSTEM, path + "/apexdata/" + name)) {
return false;
}
}
return true;
}
static bool prepare_subdirs(const std::string& volume_uuid, int user_id, int flags) {
struct selabel_handle* sehandle = selinux_android_file_context_handle();
if (!sehandle) {
LOG(ERROR) << "Failed to get SELinux file contexts handle";
return false;
}
if (flags & android::os::IVold::STORAGE_FLAG_DE) {
auto user_de_path = android::vold::BuildDataUserDePath(volume_uuid, user_id);
if (!prepare_dir_for_user(sehandle, 0771, AID_SYSTEM, AID_SYSTEM, user_de_path, user_id)) {
return false;
}
auto misc_de_path = android::vold::BuildDataMiscDePath(volume_uuid, user_id);
if (!prepare_dir_for_user(sehandle, 0771, AID_SYSTEM, AID_SYSTEM,
misc_de_path + "/sdksandbox", user_id)) {
return false;
}
if (volume_uuid.empty()) {
if (!prepare_dir(sehandle, 0700, 0, 0, misc_de_path + "/vold")) return false;
if (!prepare_dir(sehandle, 0700, 0, 0, misc_de_path + "/storaged")) return false;
if (!prepare_dir(sehandle, 0700, 0, 0, misc_de_path + "/rollback")) return false;
// TODO: Return false if this returns false once sure this should succeed.
prepare_dir(sehandle, 0700, 0, 0, misc_de_path + "/apexrollback");
prepare_apex_subdirs(sehandle, misc_de_path);
auto profiles_de_path = android::vold::BuildDataProfilesDePath(user_id);
if (!prepare_dir_for_user(sehandle, 0771, AID_SYSTEM, AID_SYSTEM, profiles_de_path,
user_id)) {
return false;
}
auto vendor_de_path = android::vold::BuildDataVendorDePath(user_id);
if (!prepare_dir(sehandle, 0700, AID_SYSTEM, AID_SYSTEM, vendor_de_path + "/fpdata")) {
return false;
}
auto facedata_path = vendor_de_path + "/facedata";
if (!prepare_dir(sehandle, 0700, AID_SYSTEM, AID_SYSTEM, facedata_path)) {
return false;
}
}
}
if (flags & android::os::IVold::STORAGE_FLAG_CE) {
auto user_ce_path = android::vold::BuildDataUserCePath(volume_uuid, user_id);
if (!prepare_dir_for_user(sehandle, 0771, AID_SYSTEM, AID_SYSTEM, user_ce_path, user_id)) {
return false;
}
auto misc_ce_path = android::vold::BuildDataMiscCePath(volume_uuid, user_id);
if (!prepare_dir_for_user(sehandle, 0771, AID_SYSTEM, AID_SYSTEM,
misc_ce_path + "/sdksandbox", user_id)) {
return false;
}
if (volume_uuid.empty()) {
if (!prepare_dir(sehandle, 0700, 0, 0, misc_ce_path + "/vold")) return false;
if (!prepare_dir(sehandle, 0700, 0, 0, misc_ce_path + "/storaged")) return false;
if (!prepare_dir(sehandle, 0700, 0, 0, misc_ce_path + "/rollback")) return false;
// TODO: Return false if this returns false once sure this should succeed.
prepare_dir(sehandle, 0700, 0, 0, misc_ce_path + "/apexrollback");
prepare_apex_subdirs(sehandle, misc_ce_path);
// Give gmscore (who runs in cache group) access to the checkin directory. Also provide
// the user id to set the correct selinux mls_level.
if (!prepare_dir_for_user(sehandle, 0770, AID_SYSTEM, AID_CACHE,
misc_ce_path + "/checkin", user_id)) {
// TODO(b/203742483) the checkin directory was created with the wrong permission &
// context. Delete the directory to get these devices out of the bad state. Revert
// the change once the droidfood population is on newer build.
LOG(INFO) << "Failed to prepare the checkin directory, deleting for recreation";
android::vold::DeleteDirContentsAndDir(misc_ce_path + "/checkin");
if (!prepare_dir_for_user(sehandle, 0770, AID_SYSTEM, AID_CACHE,
misc_ce_path + "/checkin", user_id)) {
return false;
}
}
auto system_ce_path = android::vold::BuildDataSystemCePath(user_id);
if (!prepare_dir(sehandle, 0700, AID_SYSTEM, AID_SYSTEM, system_ce_path + "/backup")) {
return false;
}
if (!prepare_dir(sehandle, 0700, AID_SYSTEM, AID_SYSTEM,
system_ce_path + "/backup_stage")) {
return false;
}
auto vendor_ce_path = android::vold::BuildDataVendorCePath(user_id);
auto facedata_path = vendor_ce_path + "/facedata";
if (!prepare_dir(sehandle, 0700, AID_SYSTEM, AID_SYSTEM, facedata_path)) {
return false;
}
}
}
return true;
}
static bool destroy_subdirs(const std::string& volume_uuid, int user_id, int flags) {
bool res = true;
if (flags & android::os::IVold::STORAGE_FLAG_CE) {
auto misc_ce_path = android::vold::BuildDataMiscCePath(volume_uuid, user_id);
res &= rmrf_contents(misc_ce_path);
if (volume_uuid.empty()) {
auto vendor_ce_path = android::vold::BuildDataVendorCePath(user_id);
res &= rmrf_contents(vendor_ce_path);
}
}
if (flags & android::os::IVold::STORAGE_FLAG_DE) {
auto misc_de_path = android::vold::BuildDataMiscDePath(volume_uuid, user_id);
res &= rmrf_contents(misc_de_path);
if (volume_uuid.empty()) {
auto vendor_de_path = android::vold::BuildDataVendorDePath(user_id);
res &= rmrf_contents(vendor_de_path);
}
}
return res;
}
int main(int argc, const char* const argv[]) {
android::base::InitLogging(const_cast<char**>(argv));
std::vector<std::string> args(argv + 1, argv + argc);
if (args.size() != 4 || !valid_uuid(args[1]) || !small_int(args[2]) || !small_int(args[3])) {
usage(argv[0]);
return -1;
}
auto volume_uuid = args[1];
int user_id = stoi(args[2]);
int flags = stoi(args[3]);
if (args[0] == "prepare") {
if (!prepare_subdirs(volume_uuid, user_id, flags)) return -1;
} else if (args[0] == "destroy") {
if (!destroy_subdirs(volume_uuid, user_id, flags)) return -1;
} else {
usage(argv[0]);
return -1;
}
return 0;
}
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